Beware of Bus-Powered USB Drives

A few weeks after Western Digital announced a 320-Gbyte version of its internal 2.5-inch Scorpio drive, the company said Monday that it has designed the latest iteration of its USB-powered portable Passport hard drive ($229.99, available from major e-tailers) around the technology. As I was reading this, I flashed back to a snippet of conversation I overheard at Best Buy over the weekend: basically, “Don’t buy bus-powered drives, dude. They suck.”

And that’s true: they do suck, but only in certain cases. Moreover, it’s a problem that drive makers like WD admit, but completely gloss over. But in some cases, it’s not their fault.

What makes this a thorny problem is the fact that the drives don’t actually fail, but simply don’t draw enough power — which means that they don’t work, but aren’t actually broken. They may copy a small file just fine, but they may run out of juice when transferring a large multi-gigabyte block of files.

Fortunately for Passport customers, this FAQ on WD’s web site solves the problem, but how many users would equate “Ack! My bus-powered hard drive stopped working!!” with the question’s title,” How do I install a WD Passport external USB hard drive in Windows or MAC?” The obvious answer is: “You hook it up to the USB port and it just works. Duh.”

And look how confusing the problem actually is. Here’s what WD says about the matter, buried straight at the bottom of the question referenced above:

First, there are problems with Macs:

“IMPORTANT: You must connect the Passport drive to the USB ports built into the Macintosh computer, not the USB ports on the supplied Macintosh keyboard. The Macintosh keyboard does not supply enough power through the USB connection to power the drive.”
But that’s not all. In fact, you may run into issues if you don’t have the proper cable, a cheap hub, an ill-designed laptop, or if you fail to make the proper sacrifice to Thor, god of thunder, while formatting. (I made the last part up; it needs to be done before formatting, apparently.) Anyway:

“USING AN EXTERNAL POWER SUPPLY

This portable USB device is powered by the USB bus and does not require a separate power supply when connected to most computers. An external power supply may be needed if you are using the following:

* A laptop computer that has limited bus power.
* USB cable that is longer than 22 inches
* USB bus-powered hub (In this case, you must connect the optional power supply to the Passport drive before connecting the USB cable to the hub).

If external power is needed, use WD’s optional power supply available from the Western Digital Online Store. WD’s power supply is guaranteed compatible with this portable USB device, with specifications defined as Class 2 and rated 5.0 VDC, 1.0A.”

I’ve used WD as an example here, but you may find similar problems with other drives from other manufacturers. A good rule of thumb, as some have discovered, is simply to be sure you use the USB cable that ships with the drive — and don’t connect that cable to a USB hub, either. The cable length may be shorter than what you’re used to, but it’s also designed to work.

Here’s the question: can this problem be solved, or is it an issue that will perpetually plague bus-powered USB drives? A WD PR representative I just spoke to initially said she thought that this would be a perpetual problem, but pledged to look into it. I know that drive makers sell their products primarily on capacity and performance. But consumers also want reliability — and they don’t just demand it, they expect it.